Reset lockout for circuit interrupting device

ABSTRACT

Resettable circuit interrupting devices, such as GFCI devices, that include a reset lock-out mechanism are provided. The reset lock-out mechanism prevents the resetting of electrical connections between input and output conductors if the circuit interrupting mechanism used to break the connection is non-operational or if an open neutral condition exists.

BACKGROUND

1. Field

The present application is directed to the family of resettable circuitinterrupting devices and systems which include, without limitation,ground fault circuit interrupters (GFCI's), arc fault circuitinterrupters (AFCI's), immersion detection circuit interrupters(IDCI's), appliance leakage circuit interrupters (ALCI's), circuitbreakers, contactors, latching relays and solenoid mechanisms. Moreparticularly, the present application is directed to a reset system insuch devices and systems which is capable of being "locked out" suchthat it cannot be reset by a user if a portion of a circuit interruptingmechanism becomes non-operational or if an open neutral conditionexists.

2. Description of the Related Art

The electrical wiring device industry has witnessed an increasing callfor circuit breaking devices or systems which are designed to interruptpower to various loads, such as household appliances, consumerelectrical products and branch circuits. In particular, electrical codesrequire electrical circuits in home bathrooms and kitchens to beequipped with ground fault circuit interrupters, for example. Presentlyavailable GFCI devices, such as the device described in commonly ownedU.S. Pat. No. 4,595,894, use a trip mechanism to mechanically break anelectrical connection between one or more input and output conductors.Such devices are resettable after they are tripped by, for example, thedetection of a ground fault. In the device discussed in the '894 patent,the trip mechanism used to cause the mechanical breaking of the circuit(i.e., the connection between input and output conductors) includes asolenoid (or trip coil). A test button is used to test the tripmechanism and circuitry used to sense faults and a reset button is usedto reset the electrical connection between input and output conductors.

However, instances may arise where an abnormal condition, caused by forexample a lightening strike, occurs which may result not only in a surgeof electricity at the device and a tripping of the device but also adisabling of the trip mechanism used to cause the mechanical breaking ofthe circuit. This may occur without the knowledge of the user. Undersuch circumstances an unknowing user, faced with a GFCI which hastripped, may press the reset button which, in turn, will cause thedevice with an inoperative trip mechanism to be reset without the groundfault protection available.

Further, an open neutral condition, which is defined in UnderwritersLaboratories (UL) Standard PAG 943A, may exist with the electrical wiressupplying electrical power to such GFCI devices. If an open neutralcondition exists with the neutral wire on the line (verses load) side ofthe GFCI device, an instance may arise where a current path is createdfrom the phase (or hot) wire supplying power to the GFCI device throughthe load side of the device and a person to ground. In the event that anopen neutral condition exists, current GFCI devices which have tripped,may be reset even though the open neutral condition may remain.

SUMMARY

The present application relates to resettable circuit interruptingdevices, such as but not limited to GFCI devices, that include a resetlock-out mechanism which prevents the resetting of electricalconnections (or continuity) between input and output conductors if thecircuit interrupter used to break the connection is non-operational orif an open neutral condition exists.

The circuit interrupter includes a trip mechanism used to cause themechanical or electrical breaking of continuity between the input andoutput conductive paths or conductors and the sensing circuitry used tosense faults.

In one embodiment, the circuit interrupting device includes a housing,an input conductive path and an output conductive path. Preferably, theinput conductive path is disposed at least partially within the housingand is capable of being electrically connected to a source ofelectricity. Preferably, the output conductive path is also disposed atleast partially within the housing and is capable of conductingelectrical current to a load when electrical continuity is establishedwith the input conductive path. Electrical continuity between theconductive paths may be established using electro-mechanical mechanisms,such as movable electrical contacts and solenoids, or usingsemiconductor type switching devices. The device also includes a circuitinterrupter disposed within the housing and configured to breakelectrical continuity between the input and output conductive paths inresponse to the occurrence of a predetermined condition. Predeterminedconditions include, without limitation, ground faults, arc faults,appliance leakage faults, immersion faults and a test cycle.

In response to the occurrence of the predetermined condition, a resetlock-out operable in a lock-out position or state and in a resetposition or state is set to one of the states. In the lock-out positionor state, the reset lock-out inhibits resetting of electrical continuitybetween the input and output conductive paths, and in the reset positionor state, the reset lock-out does not inhibit resetting of electricalcontinuity between the input and output conductive paths. The circuitinterrupting device also includes a reset mechanism operativelyassociated with the reset lock-out and the circuit interrupter.Activation of the reset mechanism activates the circuit interrupterwhich facilitates changing the operable position or state of the resetlock-out from the lock-out position or state to the reset position orstate.

In another embodiment, the circuit interrupting device includes ahousing, an input conductor disposed at least partially within thehousing and capable of being electrically connected to a source ofelectricity, and an output conductor disposed at least partially withinthe housing and capable of conducting electrical current to a load whenelectrically connected to the input conductor. In this embodiment,electrical connections between the conductors may be established usingelectro-mechanical mechanisms or semiconductor type switching devices.

The device also includes a circuit interrupter that is disposed withinthe housing and configured to break the electrical connection betweenthe input and output conductors in response to the occurrence of apredetermined condition. Again, predetermined conditions include,without limitation, ground faults, arc faults, appliance leakage faults,immersion faults and a test cycle. In response to the occurrence of thepredetermined condition, a reset lock-out operable between a lock-outposition (or state) and a reset position (or state) is set to one of thepositions. In the lock-out position, the reset lock-out inhibitsresetting of the electrical connection between the input and outputconductors, and in the reset position, the reset lock-out does notinhibit resetting of the electrical connection between the input andoutput conductors. The circuit interrupting device also includes a resetmechanism operatively associated with the reset lock-out and the circuitinterrupter. Activation of the reset mechanism activates the circuitinterrupter which facilitates changing the operable position of thereset lock-out from the lock-out position to the reset position.

The circuit interrupter includes a trip mechanism and fault sensingcircuitry. The trip mechanism may be an electro-mechanical mechanism(e.g., a solenoid or relay), a solid state mechanism or other mechanismsthat may be used to break electrical continuity. A preferredelectro-mechanical trip mechanism includes a coil assembly, a movableplunger and a banger. The movable plunger is responsive to energizing ofthe coil assembly, and the banger, which is attached to the plunger,moves when the plunger moves. Movement of the banger permits the resetlock-out to change operable positions.

Preferably, the reset mechanism includes a reset button that is coupledto the reset lock-out, and reset contacts that are activated when thereset button is depressed. When the reset button is depressed, the resetcontacts close a circuit that, in the embodiment shown, activates thetest cycle causing the circuit interrupter to activate permitting thereset lock-out to change operable positions.

This arrangement prevents the circuit interrupting device from beingreset if the circuit interrupter is inoperative, since the circuitinterrupter has to be activated in order to reset electrical continuitybetween the input and output conductive paths or conductors. In otherwords, this arrangement ensures that once the circuit interruptingdevice has been reset, it has the ability to again break electricalcontinuity between the input and output conductive paths because thesensing circuitry and trip mechanism of the circuit interrupter areutilized for resetting the continuity.

This arrangement also ensures that when such circuit interruptingdevices are initially installed and energized the proper electricalconnections have been made. For example, if the circuit interruptingdevice is a GFCI receptacle, improper electrical connections betweeninput and output conductors on the receptacle and the line (hot) andload wires in a household junction box may cause a fault that is sensedby the circuit interrupter causing its trip mechanism to activate.

In addition, in the embodiments where the trip mechanism of the circuitinterrupter uses power supplied to the device in order to activate, thearrangement of tying the resetting of the device with the operation ofthe circuit interrupter also prevents the circuit interrupting devicefrom being reset if an open neutral condition exists with the wiringsupplying electrical power to the device, since the circuit interrupterhas to be activated in order to reset electrical continuity between theinput and output conductive paths or conductors.

The present application also relates to a method for interrupting andresetting electrical connections in fault interrupting devices, such asthe device above. The method involves sensing the occurrence of apredefined condition and breaking electrical continuity between inputand output conductive paths or conductors when the predefined conditionis sensed. Preferably, a circuit interrupter having the above-describedcoil assembly, plunger and banger, is used to break continuity betweenthe conductive paths.

After electrical continuity between the input and output conductivepaths is broken, a lock-out mechanism is enabled so as to inhibitreestablishing electrical continuity between the input and outputconductive paths. To reset the device, a reset mechanism is activatedcausing the circuit interrupter to operate and thus disable the lock-outmechanism and electrical continuity between the input and outputconductive paths to be reestablished.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present application are described hereinwith reference to the drawings in which similar elements are givensimilar reference characters, wherein:

FIG. 1 is a perspective view of a ground fault circuit interruptingdevice according to the present application;

FIG. 2 is side elevational view, partly in section, of a reset mechanismfor the GFCI device shown in FIG. 1, illustrating components of thereset mechanism and the GFCI device in a set or circuit making position;

FIG. 3 is a side elevational view similar to FIG. 2, illustratingcomponents of the reset mechanism for the GFCI device in a circuitbreaking or interrupting position;

FIG. 4 is a side elevational view similar to FIG. 2, illustrating thecomponents of the reset mechanism after a reset button has beendepressed;

FIGS. 5-7 are schematic representations of one embodiment of the resetmechanism of the present application, illustrating a latching memberused to make an electrical connection between input and outputconductors and to relate the reset mechanism of the electricalconnection with the operation of the trip mechanism; and

FIG. 8 is a schematic diagram of a circuit for detecting ground faultsand resetting the GFCI device of FIG. 1.

DETAILED DESCRIPTION

The present application provides a reset lock-out mechanism forresettable circuit interrupting devices, such as GFCI devices, thatrelates the resetting of electrical connections between input and outputconductive paths or conductors to the operation of a circuit interrupteror circuit interrupting mechanism.

For the purposes of the present application, the reset lock-outmechanism according to the present application shown in the drawings anddescribed hereinbelow is incorporated in a GFCI receptacle suitable forinstallation in a single-gang junction box in a home. However, the resetlock-out mechanism according to the present application can be includedin any of the various devices in the family of resettable circuitinterrupting devices, including ground fault circuit interrupters(GFCI's), arc fault circuit interrupters (AFCI's), immersion detectioncircuit interrupters (IDCI's), appliance leakage circuit interrupters(ALCI's).

Turning now to FIG. 1, the GFCI receptacle 10 has a housing 12consisting of a relatively central body 14 to which a face or coverportion 16 and a rear portion 18 are removably secured. The face portion16 has entry ports 20 for receiving normal or polarized prongs of a maleplug of the type normally found at the end of a lamp or appliance cordset (not shown), as well as ground-prong-receiving openings 22 toaccommodate a three-wire plug. The receptacle also includes a mountingstrap 24 used to fasten the receptacle to a junction box.

A test button 26 extends through opening 28 in the face portion 16 ofthe housing 12. The test button is used to activate a test cycle, whichtest the operation of a circuit interrupter (or circuit interruptingmechanism) disposed in the device. The circuit interrupter, to bedescribed in more detail below, is used to break electrical continuitybetween input and output conductive paths (or conductors). A resetbutton 30 forming a part of a reset mechanism extends through opening 32in the face portion 16 of the housing 12. The reset button is used toactivate a reset cycle, which reestablishes electrical continuitybetween the input and output conductive paths or conductors.

Electrical connections to existing household electrical wiring are madevia binding screws 34 and 36, where screw 34 is an input (or line)connection point and screw 36 is an output (or load) connection point.It should be noted that two additional binding screws (not shown) arelocated on the opposite side of the receptacle 10. Similar to bindingscrews 34 and 36, these additional binding screws provide input andoutput connection points. Further, the input connections are for lineside phase (hot) and neutral conductors of the household wiring, and theoutput connections are for load side phase (hot) and neutral conductorsof the household wiring. The plug connections are also considered outputconductors. A more detailed description of a GFCI receptacle is providedin U.S. Pat. No. 4,595,894 which is incorporated herein in its entiretyby reference.

Referring now to FIG. 2 there is shown mechanical components of trip andreset mechanism according to one embodiment of the present application.Although the trip and reset mechanisms shown in the drawings areelectro-mechanical in nature, the present application also contemplatesusing semiconductor type trip and reset mechanisms, as well as othermechanisms capable or making and breaking electrical continuity.

The trip mechanism includes a coil assembly 50, a plunger 52 responsiveto the energizing and de-energizing of the coil assembly and a banger 54connected to the plunger 52. The banger 54 has a pair of banger dogs 56and 58 which are used to set and reset the connection between input andoutput conductors. The trip mechanism is activated in response to thesensing of a ground fault by, for example, the electronic circuitryshown in FIG. 8. FIG. 8 includes a conventional circuitry for detectingground faults that includes a differential transformer that sensescurrent inbalances. As noted, the trip mechanism and fault sensingcircuitry are included in the circuit interrupter.

The reset mechanism includes reset button 30, movable latching member 60connected to the reset button 30 and reset contacts 62 and 63 thattemporarily activate the trip mechanism when the reset button isdepressed. Preferably, the reset contacts 62 and 63 are normally openmomentary contacts.

FIGS. 2-4 show the mechanical components of the trip and resetmechanisms in various stages of operation. In FIG. 2, the GFCIreceptacle is shown in a set position where movable contact arm 70 is ina stressed condition so that movable contact 72 is in electricalengagement with fixed contact 74 of contact arm 76. Referring to FIG. 3,if the sensing circuitry of the GFCI receptacle senses a ground fault orif the test button 26 is depressed, the coil assembly 50 is energized todraw plunger 52 into the coil assembly 50 so that banger 54 movesupwardly. As the banger moves upwardly, the banger front dog 58 strikesthe latch member 60 causing it to pivot in a counterclockwise directionabout the joint created by the top edge 82 and inner surface 84 offinger 80. The movement of the latch member 60 removes the latchingfinger 64 from engagement with side R of the remote end 73 of themovable contact arm 70, and permits contact arm 70 to return to itspre-stressed condition opening contacts 72 and 74. It should be notedthat the description thus far has been in terms of a single latch member60 and a single contact arm 70. However, there are preferably two setsof latch members 60 and contact arms 70: one set for the inputconductors; and the other set for the output conductors. Further, thebanger 54 preferably has two sets of banger dogs: one set for the phase(or hot) conductors; and the other set for the neutral conductors.

After tripping, the coil assembly 50 is de-energized so that spring 53returns plunger 52 to its original extended position and banger 54 movesto its original position releasing latch member 60. At this time thelatch member 60 is in a lock-out position where latch finger 64 inhibitsmovable contact 72 from engaging fixed contact 74, as seen in FIG. 6.

To reset the GFCI receptacle so that contacts 72 and 74 are closed andcontinuity between the input and output conductors is reestablished, thereset button 30 is depressed sufficiently to overcome the bias force ofreturn spring 90 and move the latch member 60 in the direction of arrowA, seen in FIG. 4. While the reset button 30 is being depressed, latchfinger 64 contacts side L of the movable contact arm 70 and continueddepression of the reset button 30 forces the latch member to overcomethe stress force exerted by the arm 70 causing the reset contact 62 onthe arm 70 to close on reset contact 63. Closing the reset contactscompletes a test circuit so that the test cycle is activated. Asdescribed above, during the test cycle the plunger 52 moves the banger54 upwardly so that the banger 54 strikes the latch member 60 pivotingthe latch finger 64 while the latch member 60 continues to move in thedirection of arrow A. As a result, the latch finger 64 is lifted overside L of the remote end 73 of the movable contact arm 70 onto side R ofthe remote end of the movable contact arm, as seen in FIG. 7.

After tripping, the coil assembly 50 is de-energized so that so thatplunger 52 returns to its original extended position, and banger 54releases the latch member 60 so that the latch finger 64 is in a resetposition, seen in FIG. 5. Release of the reset button causes thelatching member 60 and movable contact arm 70 to move in the directionof arrow B until contact 72 electrically engages contact 74.

Using the reset lock-out feature described above permits the resettingof the GFCI device or any of the other devices in the family of circuitinterrupting devices only if the circuit interrupter (or circuitinterrupting mechanism) is operational.

While there have been shown and described and pointed out thefundamental features of the invention as applied to the preferredembodiment, as is presently contemplated for carrying them out, it willbe understood that various omissions and substitutions and changes ofthe form and details of the device described and illustrated and in itsoperation may be made by those skilled in the art, without departingfrom the spirit of the invention.

What is claimed:
 1. A circuit interrupting device comprising:a housing;at least one input conductor disposed at least partially within saidhousing and capable of being electrically connected to a source ofelectricity; at least one output conductor disposed within said housingand capable of conducting electrical current to a load when electricallyconnected to said at least one input conductor; a circuit interrupterdisposed within said housing and configured to break said electricalconnection between said input and output conductors in response to theoccurrence of a predetermined condition; a reset lock-out responsive tothe occurrence of said predefined condition such that said resetlock-out is operable between a lock-out position wherein said resetlock-out inhibits resetting of said electrical connection between saidinput and output conductors and a reset position wherein said resetlock-out does not inhibit resetting of said electrical connectionbetween said input and output conductors; and a reset mechanismoperatively associated with said reset lock-out and said circuitinterrupter such that activation of said reset mechanism activates saidcircuit interrupter which facilitates movement of said reset lock-outfrom said lock-out position to said reset position by said resetmechanism.
 2. The circuit interrupting device according to claim 1,wherein said circuit interrupter comprises a coil assembly, a movableplunger responsive to energizing of said coil assembly and a bangerattached to said plunger such that movement of said plunger istranslated to movement of said banger and movement of said banger causessaid reset lock-out to operate in said lock-out position or said resetposition.
 3. The circuit interrupting device according to claim 2,wherein said input conductor has an electrical contact attached theretoand said output conductor has an electrical contact attached thereto,and at least one of said conductors is movable relative to the othersuch that said electrical connection is made when said input and outputcontacts are closed.
 4. The circuit interrupting device according toclaim 3, wherein when said reset lock-out is in said lock-out positionsaid contacts are inhibited from closing.
 5. The circuit interruptingdevice according to claim 1, wherein said reset mechanism comprises:areset button coupled to said reset lock-out; and a reset contact that isactivated when said reset button is depressed.
 6. The circuitinterrupting device according to claim 1, wherein said predeterminedcondition comprises a ground fault, an arc fault, an appliance leakagefault, an immersion fault or a test cycle.
 7. A ground fault circuitinterrupting device comprising:a housing; at least one input conductordisposed at least partially within said housing and capable of beingelectrically connected to a source of electricity; at least one outputconductor disposed within said housing an capable of conductingelectrical current to a load when electrically connected to said atleast one input conductor; a circuit interrupter disposed within saidhousing and configured to break said electrical connection between saidinput and output conductors in response to the occurrence of a groundfault or test cycle; and a reset mechanism having a reset lock-outresponsive to activation of said circuit interrupter so as to be movablebetween a lock-out position wherein said reset lock-out inhibitsresetting of said electrical connection between said input and outputconductors and a reset position wherein said reset lock-out does notinhibit resetting of said electrical connection between said input andoutput conductors, wherein when said reset mechanism is activated saidcircuit interrupter is activated to facilitates movement of said resetlock-out from said lock-out position to said reset position by saidreset mechanism and resets said electrical connection between said inputand output conductors.
 8. The ground fault circuit interrupting deviceaccording to claim 7, wherein said circuit interrupter comprises a coilassembly, a movable plunger responsive to energizing of said coilassembly and a banger attached to said plunger such that movement ofsaid plunger is translated to movement of said banger and movement ofsaid banger causes said reset lock-out to operate in said lock-outposition or said reset position.
 9. The ground fault circuitinterrupting device according to claim 8, wherein said input conductorhas an electrical contact attached thereto and said output conductor hasan electrical contact attached thereto, and at least one of saidconductors is movable relative to the other such that said electricalconnection is made when said input and output contacts are closed. 10.The ground fault circuit interrupting device according to claim 9,wherein when said reset lock-out is in said lock-out position saidcontacts are inhibited from closing.
 11. The ground fault circuitinterrupting device according to claim 7, wherein said reset mechanismcomprises:a reset button coupled to said reset lock-out; and at leastone reset contact that is activated when said reset button is depressed.12. A circuit interrupting device comprising:housing means; inputconductor means disposed at least partially within said housing meansand capable of being electrically connected to a source of electricity;output conductor means disposed at least partially within said housingmeans and capable of conducting electrical current to a load whenelectrically connected to said input conductor means; circuitinterrupting means disposed within said housing means for breaking saidelectrical connection between said input and output conductor means inresponse to the occurrence of a predetermined condition; reset lock-outmeans responsive to activation of said circuit interrupting means forinhibiting resetting of said electrical connection between said inputand output conductor means after said circuit interrupting means breakssaid connection between said input and output conductor means; and resetmeans disposed within said housing means for activating said circuitinterrupting means so that said lock-out means does not inhibitresetting of said electrical connection between said input and outputconductor means and for resetting said electrical connection betweensaid input and output conductor means.
 13. The circuit interruptingdevice according to claim 12, wherein said circuit interrupting meanscomprises a coil means, movable plunger means responsive to energizingof said coil means and banger means attached to said plunger means suchthat movement of said plunger means is translated to movement of saidbanger means and movement of said banger means causes said resetlock-out means to operate in a lock-out position, wherein said input andoutput contact means are inhibited from closing or a reset position,wherein said input and output contact means are not inhibited fromclosing.
 14. The circuit interrupting device according to claim 13,wherein said input conductor means includes electrical contact means andsaid output conductor means includes electrical contact means, andwherein at least one of said conductor means is movable relative to theother such that said electrical connection is made when said input andoutput contacts means are closed.
 15. The circuit interrupting deviceaccording to claim 12, wherein said reset means comprises:a reset buttoncoupled to said reset lock-out means; and reset contact means that isactivated when said reset button is depressed.
 16. The circuitinterrupting device according to claim 12, wherein said predeterminedcondition comprises a ground fault, an arc fault, an appliance leakagefault, an immersion fault or a test cycle.
 17. A method for interruptingand resetting electrical connections in fault interrupting deviceshaving a housing, an input conductor disposed at least partially withinthe housing and electrically connected to a source of electricity, andan output conductor disposed at least partially within the housing andcapable of conducting electrical current to a load when electricalcontinuity between the input and output conductors is made, said methodcomprising:sensing the occurrence of a predefined condition; breakingelectrical continuity between the input and output conductors when saidpredefined condition is sensed using a circuit interrupting mechanism;enabling a lock-out mechanism to inhibit the making of electricalcontinuity between the input and output conductors after breakingelectrical continuity between said conductors; and activating a resetmechanism that activates said circuit interrupting mechanism to disablesaid lock-out mechanism and makes electrical continuity between saidinput and output conductors.
 18. The method according to claim 17,wherein said predefined condition comprises a ground fault, an arcfault, an appliance leakage fault, an immersion fault or a test cycle.